[flang-commits] [flang] [flang][cuda] Allow list-directed PRINT and WRITE stmt in device code (PR #87415)

[Peter Klausler via flang-commits]

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@@ -275,9 +275,74 @@ template <bool IsCUFKernelDo> class DeviceContextChecker {
         },
         ec.u);
   }
+  template <typename SEEK, typename A>
+  static const auto *GetIOControl(const A &stmt) {
+    for (const auto &spec : stmt.controls) {
+      if (const auto *result = std::get_if<SEEK>(&spec.u)) {
+        return result;
+      }
+    }
+    return static_cast<const SEEK *>(nullptr);
+  }
+  template <typename A> static bool IsInternalIO(const A &stmt) {
+    if (stmt.iounit.has_value()) {
+      return std::holds_alternative<Fortran::parser::Variable>(stmt.iounit->u);
+    }
+    if (auto *unit = GetIOControl<Fortran::parser::IoUnit>(stmt)) {
+      return std::holds_alternative<Fortran::parser::Variable>(unit->u);
+    }
+    return false;
+  }
+  void WarnOnIoStmt(const parser::CharBlock &source) {
+    context_.Say(
+        source, "I/O statement might not be supported on device"_warn_en_US);
+  }
+  template <typename A>
+  void WarnIfNotInternal(const A &stmt, const parser::CharBlock &source) {
+    if (!IsInternalIO(stmt)) {
+      WarnOnIoStmt(source);
+    }
+  }
   void Check(const parser::ActionStmt &stmt, const parser::CharBlock &source) {
     common::visit(
         common::visitors{
+            [&](const common::Indirection<parser::PrintStmt> &) {},
+            [&](const common::Indirection<parser::WriteStmt> &x) {
+              if (x.value().format) { // Formatted write to '*' or '6'
+                if (std::holds_alternative<Fortran::parser::Star>(
+                        x.value().format->u)) {
+                  if (x.value().iounit) {
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klausler wrote:

This `if` construct is not useful if the code is just going to always `return` anyway afterwards.

https://github.com/llvm/llvm-project/pull/87415